Torpedo for shooting oil wells



July 5, 1932. M. D. MITCHELL TORPEDO FOR SHOOTING OIL WELLS Filed July 29, 1922. I 2 Sheets-Sheet l July 5, 1932. M. D. MITCHELL TORPEDQ FOR SHOOTING OIL WELLS 2 Sheets-Shet 2 Filed July 29, 1922 Patented July 5, .1932

PATENT OFFICE m3: 1;. Mrrcnmm, or mnnrnnnnircn mnsns ronrnno ron snoorme on. wnnns Application filed July 29, 1922. Serial No. 578,387.

7 It-is a-common practice in the operation of oil wells to explode a charge of nitroglycerine or other hi h explosive in a well at the level of the oil caring rock for the purpose of giving better access of the oil to the pocket 1n the well. For'this purpose the charge of nitroglycerine is lowered to the proper position and detonated electrically by means w which need not be described herein. This equires the use of wires extending from the battery above ground to the detonator which frequently become broken or short circuited.

I Thus many cases during the drilling of the Will the wall of the hole caves in generally well down toward the bottom of the hole. When this happens it is necessary to shut off the cave by means of a string of easing covering the caved or loose portion. When the casing is pulled, rocks, etc. is apt to 80 fall upon the shot; As the wires connected to the shot rumthrough the casing the latter must be pulled out over the wires and this 1 results in a considerable loss of time due to handling the wires, the insulation on the 2 wires is frequently broken and a short circuitthereby created or thecave falls in on the wires and breaks them, requiring an expensive replacement. My invention dispenses with the use of an electrically operated det- 80 onator and hence with the complications and difiiculties resulting from the use of the 'wires to which reference has been made above.

My invention comprises a timed detonator which may be set to explode at any desired tirely self-contained so that it may be lowered on top of the main charge of explosive to detonate the latter. Being entirely self-contained it is not affected by the withdrawal of the casing orby the fall of material from the wall of the hole. My improved device comprises a shellnr containenenclosing a relatively small charge of high exhamme-r or firingpin for exploding the detonating charge. It is necessary that the container and its contents be heavier than water and that the container be water-tight and capable of resisting great pressure of water erine.

period after the setting and which is en-.

plosive, a detonator and a clock-controlled.

which may occupy the hole for some distance above it.

In the accompanying drawings, Fig. 1 is a side elevation artly in section of a detonator or shot embo ying my invention; Fig. 2 a transverse horizontal section of the same; Fig. 3a plan of a detail; and Fig. 4: a vertical section of an oil well showing the detonator and main charges of explosive in place, the former being not yet released from 00 the lowering wire or cable. p

' In the specific form of the invention chosen for exemplification, the container 4: is shown as of malleable iron, generally cylindrical and with a rounded lower end. It is divided into an upper and a lower compartment, the uppercompartment receiving a clock mechanismlO and the lower compartment 6 being filled with high explosivesuch as nitroglyc- The diaphragm or partition 5 di- 7 viding the chambers includes a horizontal portion 5* and a vertical portion 5?, the former constituting a support for the clock work and the latter formin'ga vertical extension 8 of the lower chamber 6. It is tobennderstood that in use, the chamber 6 and the vertical extension thereof are filled with the explosive. A detonator 9 is mounted in the vertical portion of the diaphragm.

The clock work 10 may be of any familiar 8 or suitable type, the ordinary round clock being shown in the drawings. The usual spindle 11 on which the hour hand of the clock is commonly mounted, extends as usual through the back of the clock casing and is provided with a knurled finger wheeLlZ by which it may be rotated. Beneath the finger wheel I i and also secured to the spindle is a snail cam 13 and the back of the clock casingis inscribed with numerals properly spaced apart in a circle concentric with said spindle and preferably corresponding to units of time. Thus in Figs. 2 and 3 I have shown 24 numerals and division marks, the spaces between the latter corresponding to half hoursl Obviously, the spindle might be made to rotate at half the speed when these marks and the numerals identified therewith would correspond to hours.

The snail cam 13 controls the firing bolt 14 and the latter is mounted in guides 15-16,- the first named of which is, mounted on the back of the clock and'the latter in the form of a thimble secured t9 theinner face of the wall of the casing. Within the thimble the bolt is provided with a head 17 and a spring a 18 of considerable power, is compressed beting the bolt to be driven against the detw tween said head and the wall of the casing 50 that when released the bolt is driven by the spring into contact with thedetonator ,9. A roller 20 is journalednn a stud, 19 on the bolt-and arranged to bear upon the snail cam 13. As the snail camrevolves the bolt is slowly withdrawn or set by means of'the engagement of the edge of the cam with the.

proof 'shell capable of withstanding: relat vely high pressure, a diaphragm 1n the shell comprising a horizontal and a vertical portion and dividing the shell into a clock' chamber-and an explosive chamber, a detonator mounted in the vertical portion of the diaphragm, a clock mounted on. the horizontal portion of the diaphragm, a recipro-- cable firing bolt above the clock and in line with the detonator, a spring for forcing the bolt toward'the detonatorand a cam operated by the clock and engaging the bolt for retracting and releasing the latter.

MARK D. MITCHELL.

roller.20 and ultimately the roller drops off of the-high point of'thecam thus permitonator. In practice, the cam is set by means of the time inscriptions so that the bolt is 7 released at the 'desiredinterval after the ca is set.

' The upper end of the casing or shell is closed by a screw cover plate 21 which has a water tight joint with the shell. The plate is provided with perforated lugs 22 which receive the ends of a bail 23 by which the det- & onating devicejs handled. At 24 I have earth through an oil well the oil bearing 1 stratum is represented at a and the superin cumbent strata at b and 0. The well casing isshown at 03 extending as usual from the surface of the earth through the superincumbent strata to the oil sand. Charges of highexplosive e are shown at the bottom of 1 the well and the detonator at f, the bail of the latter being shown as not yetdisconnected from the lowering cable g.

In shooting the well with my improved detonator the main explosive charges are first lowered into the well into the positionillustrated and the detonator afte'r'having received its charge of explosive, percussion cap and clock work, the latter set'for operation within the desired period, is closed by the; cover 21 and lowered into position after which the wire may be disconnected from the bail. Afiter the predetermined interval the clock work releases the bolt 14 which strikes and partially broken away a section of the the percussion cap setting ofl the detonator charge, the explosive of which explodes the main chargewith the usual efiect upon the o1l sand immediately. surrounding the well.

ll claim: In a device of the class described, water= 

